The printing of sublimation transfers onto a mug by heating is well known. The printing process involves the transferring of an image on the sublimation transfer by heat and contact pressure. There are many types of sublimation transfers that can be imprinted by various printing devices, for example, copy machines, laser printers, printing presses, etc. The key to all these image transfers is that they all use a form of "sublimation" ink. The sublimation transfer is made up of two basic parts: the transfer release paper, and sublimation dyes. The sublimation dyes are printed onto the transfer release paper. The heat transfer process heats the transfer paper and sublimation dye to a predetermined temperature. As the temperature of the mug rises during the heating cycle time, the sublimation dyes start to transfer from transfer paper to the mug. The transmissiveness of sublimation dyes from the transfer paper to the mug is the key to any heat transfer process. Different types of sublimation transfers transfer at different operating temperatures. However, the primary requirement for obtaining a good image transfer is the uniform heating of the mug. If there are "cold spots" around the mug due to non-uniform heating, undesirable non-uniform transfer of the dye onto the mug will occur, resulting in a low quality product.
There are various known techniques for heating a mug and image transfer for transferring the image to the mug. For example, U.S. Pat. No. 5,019,193 describes a mug press with a heated blanket. U.S. Pat. No. 4,989,508 describes a method for clamping a transfer onto a mug which is heated by hot air conduction. U.S. Pat. No. 4,874,454 describes a flexible transfer head with a flexible heating element. U.S. Pat. No. 5,244,529 describes a clamp and mug transfer system where heat is applied to the mug by an electric heating blanket. A problem associated with heating blankets are that they are expensive and have a short life. In addition, it is difficult to construct a reliable blanket that provides uniform pressure and heat. Other prior art types heating systems tend to provide non-uniform heating.
The present invention provides a unique method and apparatus that provides uniform heating of the mug, which results in excellent transfer of images, while maintaining high reliability and long life.